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Showing content with the highest reputation on 01/04/22 in all areas

  1. I am a new member, but already have benefited significantly by the forums. Posting my questions and answering or replying to others, have helped me to clarify my thoughts, to get new insights, and in one case even to solve an old problem. Understandably and unavoidably, there is a lot of noise there. It is not too difficult to filter it out and to get a positive effect. Thank you to the members and to the moderators.
    4 points
  2. Yes, this is one direction of thought. For example, see the reference here: I don't like this direction of thinking. I rather think in the opposite direction, similar to Penrose and to this: In other words, it is not math that corresponds to the physical world, but rather physical theories that correspond to math. Physical theories, to be good theories, need precision, rigor, clear concepts, they need to be free of human prejudices, psychology, vague language, etc. Math has exactly these attributes. Physical laws are described mathematically by necessity. To this argument (which is Penrose's one, not mine) I add a bit of biology. For example, humans, like all other mammals, have an area of the brain responsible for computing a "mental map" of the surroundings. It evolved because it gives obvious advantages to the organism. And of course it computes specifically 3D maps. Why would it do any other kind? We never needed to deal with any other kind. Thus, we are good in visualizing in 3D. Now, studying phenomena beyond our immediate experience, we stumbled upon other kinds. We cannot use our visual imagination and intuition, and our everyday language, to describe them. Mathematics is the only available tool.
    2 points
  3. May I reply point by point? Starting with the last point? Thank you. I didn't mean it as an offence. I didn't mean to shut you up. Please, continue commenting and explaining. Am I obligated to reply? That is what I think is not always necessary, is it? May I reply only on comments that are of interest to me? Somebody else might be interested and reply on other comments. In my opinion, discussions, unlike arguments, don't have to end in agreement or disagreement. They can just give a food for further thought.
    2 points
  4. They are a family of paleoantropologists; Louis and Mary Leakey, as well as Richard's wife, Meave. Richard Leakey was an out and out field scientist. He was raised in the African savanna, rather than an academic environment. Neither he or his parents, probably, changed the big picture of the evolution of Homo sapiens by themselves. Although his father, Louis, is credited with having found a fossil that nobody knows where to put, Homo habilis. They mostly dug the ground, described what was there, and kept looking. But they were people who knew the environment inside out. R. Leakey was very involved in wildlife management and conservation strategies too. Very interesting people all of them. Here's a sample of what Richard Leakey was. Attenborough, Dawkins, Goodall, and Leakey discussing strategies to "save the planet." (2005.) The Selfish Green: IMHO, the contributions of Goodall and Leaky are priceless, and invaluable in their effort to tie these other two great minds to the ground, if I've understood them correctly. "It's very much part of being a primate, and the whole business of being a primate is to get other primates to do what you think is right" --Richard Leakey
    2 points
  5. 62 years ago, on February 1960, Eugene Wigner concluded his article of the above title: "The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve." I think it might be interesting to discuss, if there is a better understanding of this miracle now. (Leave the issue of deserving it alone, please )
    1 point
  6. I found out today that God is MASSIVELY in favour of the death penalty. I looked up Onanism, (after a reference to masturbation) and it's a pretty good read. Judah had two sons, Er and Onan. God slew Er because he was wicked. Case closed. The death penalty is moral. Although of course, being God, he would KNOW without any doubt that Er was indeed guilty of being wicked. We mere mortals convict on REASONABLE certainty, so there is always that bit of uncertainty I guess. But in cases where there is no doubt at all, then the death penalty is moral, because God didn't just say so, he actually performed the execution himself. God then spoke to Er's younger brother, Onan, and told him to have sex with Er's widow. Onan did as he was told, but he pulled his willie out, before he came, and ejaculated on the ground. So God slew him as well. It seems he was a real fan of capital punishment. So Onan not only got killed, but he suffered the indignity of giving his name to masturbation, even though his crime was actually just pulling out. The story then follows Tamar, the widow of Er that Onan was supposed to get pregnant. She asked Judah if she could marry another of his sons, but he said no. So she dressed up as a prostitute, covered her face with a veil, and met up with Judah on his travels. Not knowing it was his daughter-in-law, Judah negotiated a price for sex with this "prostitute" , I think it was one goat, and Tamar got pregnant by him. Later, when it became obvious that Tamar was pregnant, Judah said that he would kill the man who got her pregnant, and Tamar produced the goat. So Judah realised that he had actually vowed to kill himself. It's all there in the good book. Lots of stuff that I didn't know about God. Particularly, how right wing he actually is when it comes to the death penalty. Truly, the Lord is a Republican !!
    1 point
  7. The parrot always remains as a 4D structure in the Block Universe. For thermodynamic reasons we cannot get to him. Really, he's just resting. I'm sorry, but how many more wacky dark energy tired light threads are there going to be this week?
    1 point
  8. If you read my post about this you will see I say the (kinetic) energy of the piston goes into the flywheel (and in some cases other pistons) and then comes back to the piston on its return stroke. Just as in @mistermack's sprung mass example, the kinetic energy goes into potential energy in compressing or stretching the spring and then comes back to kinetic energy again. But the total energy of the system stays constant, if there is no friction or other source of loss. That's what the crank does: transforms linear kinetic energy into rotational energy and back again. Think of a single cylinder engine. Every power stroke, the piston gives a kick to the flywheel, which is then able to move the piston back on the exhaust, induction and compression strokes, slowing down all the while, until it is given another kick by the next power stroke. The flywheel is the kinetic energy store and its speed changes throughout the cycle as it gains energy from, and loses energy to, the piston. When the piston decelerates, it does work on the crankshaft and flywheel, and then the crankshaft and flywheel do work on it to accelerate it again. No net energy loss need occur.
    1 point
  9. https://www.sciencealert.com/the-tiny-dots-in-this-image-aren-t-stars-or-galaxies-they-re-black-holes The Tiny Dots in This Image Aren't Stars or Galaxies. They're Black Holes MICHELLE STARR 2 JANUARY 2022 The image above may look like a fairly normal picture of the night sky, but what you're looking at is a lot more special than just glittering stars. Each of those white dots is an active supermassive black hole. And each of those black holes is devouring material at the heart of a galaxy millions of light-years away – that's how they could be pinpointed at all. more at link..... <<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>> Awesome!!
    1 point
  10. Einstein is not an idiot. Einstein is not, period. Just like that famous parrot: 'E's not pinin'! 'E's passed on! This parrot is no more! He has ceased to be! 'E's expired and gone to meet 'is maker! 'E's a stiff! Bereft of life, 'e rests in peace! If you hadn't nailed 'im to the perch 'e'd be pushing up the daisies! 'Is metabolic processes are now 'istory! 'E's off the twig! 'E's kicked the bucket, 'e's shuffled off 'is mortal coil, run down the curtain and joined the bleedin' choir invisible!! THIS IS AN EX-PARROT!!
    1 point
  11. http://static.projects.iq.harvard.edu/files/styles/os_files_xxlarge/public/eht/files/m87_lo_april11_polarimetric_average_image_ml_deband-cc-8bit-srgb.jpg?m=1616347517&itok=q_uJvV6S Taked by the EHT. (Event Horizon Telescope)
    1 point
  12. I could have posted a similar OP when I became active here last summer. One of the best general science forums out there. Glad you are here, Genady. And thanks to the mods here, who are a big factor in the quality of SFN.
    1 point
  13. Quite a star(t)ling sight! I'm sure Uri Geller is envious.
    1 point
  14. I think you come across as a deep observer of Nature. When we've disagreed, it's always been constructive and enriching. So thank you too!
    1 point
  15. +1 Where do you think this supposedly lost energy goes when the piston crown stops and then changes direction. Hint in order to stop it there must be a force and therefore there must be an equal and opposite reaction force on something else.
    1 point
  16. But reciprocating in itself incurs no automatic energy loss. Imagine a spring in a vacuum holding a weight. Pull it down and release it, you have a simple reciprocating motion. But it's not losing energy because of the reciprocation. The only energy loss is due to heat produced in the metal of the spring, so it will finally stop going up and down. But the reciprocation itself doesn't consume energy. The loss of kinetic energy, as the weight stops, is transferred to the spring, or back to gravitational potential. In the engine, it's being transferred back to the flywheel, or the other pistons, as one piston stops. As stated above, the energy losses are in friction and gaseous drag. If the pistons and con rods were consuming energy as you suggest, they would overheat in no time.
    1 point
  17. The signal we're looking for is always buried in noise, and alone we can only sift through so much. Discussion helps a lot, and your contributions are welcome.
    1 point
  18. It is worth noting that there are four pairs of North-South poles involved. 1) The N-S poles used for or coordinate systems eg Latitude and Longitude. 2) The N-S poles at the surface ends of the mechanical spin axis. 3) The geomagnetic N and S poles at the surface surface ends of the axis of an equivalent bar magnet, centred at the Earth's centre. 4) The magnetic N and S poles at the surface where the field lines are vertical. https://en.wikipedia.org/wiki/Geomagnetic_pole For most geological purposes, which is N and which is S make no difference. But for some including the weather and the aurora there will be differences. Life in general and particularly creatures however, will experience greater effects. Many creatures use some form of magnetic navigationand I believe even some plant life has magnetic orientation. Humans may experience some unexpected disruptions in addition. For instance the ground of electric power grids will be partially disrupted and may result in blackouts.
    1 point
  19. Yes welcome, you have shown yourself to be a cogent thinker in whatever is your discipline. +1
    1 point
  20. There may be a misunderstanding here. There is nothing energy-absorbing about the change of direction of the piston. Its momentum changes, but then so does the momentum of another piston on the crankshaft to compensate. The kinetic energy of the piston is transferred by the crankshaft to the flywheel - and/or to other pistons - and then back to the piston again as it accelerates in the opposite direction. Don't rely on YouTube videos for explanations: many of them are made by idiots or people that can't explain things properly. The main losses in a reciprocating engine, apart from thermodynamic ones, are pumping losses (obviously and inevitably) and friction losses. Both can be considerable. There are many sliding surfaces, e.g. piston rings sliding on the cylinder liner, plain bearings, cam followers against cams, and so forth. On your original question, it makes no difference how the engine is mounted in the vehicle. The momentum transfer takes place internally in a well-designed engine. Any momentum transfer that is not internally compensated will merely make the engine and vehicle vibrate at the frequency of the piston's motion. There is either way no net momentum transfer to the vehicle - unless the engine blows up and throws a piston of course. 😊
    1 point
  21. Disk failure (especially HDD which takes more energy than SSD) can be a sign of cable problems or PSU problems.. 1) replace SATA cables. 2) replace PSU. Measure the voltages on the power supply. Without a heavy load and with a heavy load. ps. All my problems with PC for the last year were caused by the PSU giving too low a voltage at random times. Periodic heavy use of the CPU/GPU, plugging in DVD drives and several drives caused them to occur faster. PSU does not have to be permanently damaged. It just can give you 4.5V instead of 5V and 11V or 13V instead of 12V. When there is heavy HDD usage, HDD is shutting down, and cannot start spinning again, until reboot. Data on NTFS is lost and logical errors start appearing on volumes. And OS becomes unstable.
    1 point
  22. As far as I know this forum is focused on mainstream science; forum members may provide arguments backed up by established mainstream theories without providing all the underlaying supporting evidence, observations and mathematics of the mainstream theory. Note that rules does not prevent a member from presenting material that goes against the mainstream and in this case the member has to provide supportive evidence. Example: Conservation of momentum may be used in an argument about mechanics without detailed explanation and evidence how and why momentum is conserved in physics. If a member argues in favour for a reactionless drive that breaks the conservation of momentum then the member is free to do so as long as a model and supportive evidence is presented. Example: Material that was speculative at one time may not be so at a later time. Had I posted an idea about a database structure that allows full trust in the decentralized and distributed public transaction ledger it would probably have been suitable for the speculations section if I posted it in 2001. Today, when blockchain is an established technique, it may be discussed in the mainstream sections. Note: I assume discussion is done good faith in the above examples.
    1 point
  23. I mean I assume that if we didn't want to eat them we would stop breeding them. Even if the livestock that exists today were to be set free, they wouldn't have anywhere near the environmental impact that the meat producing, processing, packaging, refrigeration and transport industries have. As for the uncaught fish - what stress are they causing? We don't need to: we've already eradicated many of them; many more will soon follow. The hangers-on, plus their feral ex-domestic cousins, would feast for a generation or two on the abandoned livestock and presumably restore the ecological balance that existed before 'we' messed it up.
    1 point
  24. ! Moderator Note I'm not going to fault someone for not getting responses on a narrowly-focused topic. There is a clear invitation to discussion, there are calculations and copious references for interested parties, which is in stark contrast to most speculations threads. <referee motions for play to continue>
    1 point
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